/*
 * TouchGraph LLC. Apache-Style Software License
 *
 *
 * Copyright (c) 2002 Alexander Shapiro. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:  
 *       "This product includes software developed by 
 *        TouchGraph LLC (http://www.touchgraph.com/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "TouchGraph" or "TouchGraph LLC" must not be used to endorse 
 *    or promote products derived from this software without prior written 
 *    permission.  For written permission, please contact 
 *    alex@touchgraph.com
 *
 * 5. Products derived from this software may not be called "TouchGraph",
 *    nor may "TouchGraph" appear in their name, without prior written
 *    permission of alex@touchgraph.com.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL TOUCHGRAPH OR ITS CONTRIBUTORS BE 
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR 
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE 
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, 
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 */

package com.touchgraph.graphlayout.graphelements;

import  com.touchgraph.graphlayout.Node;
 
import  java.util.Vector;

/** TGNodeQueue: a very simple queue implementation for doing a breadth
  * first search.  Should probably be implemented with linked lists.
  *   
  * @author   Alexander Shapiro                                        
  * @version  1.20
  */
public class TGNodeQueue {

    Vector queue;

    public TGNodeQueue() {
        queue=new Vector();
    }
    
    public void push( Node n ) {
        queue.addElement(n);
    }
    
    public Node pop() {
        Node n = (Node)queue.elementAt(0);
        queue.removeElementAt(0);
        return n;
    }
    
    public boolean isEmpty() {
        return queue.size() == 0;
    }
    
    public boolean contains( Node n ) {
        return queue.contains(n);
    }

} // end com.touchgraph.graphlayout.graphelements.TGNodeQueue